Pagels 2009 - candle smoke particle composition and metal emissions

Pagels and colleagues measured candle-smoke particle composition from two tapered candle types during steady burn, sooting burn, and smouldering in a controlled chamber. The study is routeable as home-air emission product context because Table 3 reports metal component emission factors for Cu, Sn, Co, Zn, and Pb from the candle-smoke particles. The source reports emission factors in µg h-1 and particle-mass emission factors in mg h-1; no product-content concentration, migration value, or consumer threshold is inferred here.

Key numbers

• Sample frame: two tapered candles made by market-leading companies in Sweden. Candle I was a white pure-stearin candle marketed as low-soot and in a higher price range. Candle II was a dark-blue budget candle made from a stearin/paraffin wax mixture.
• Experimental setup: candle smoke was generated in a 21.6 m3 stainless-steel chamber at 30 ± 5% RH and 23-28 °C, with a supply-air flow rate of 10.8 m3 h-1 corresponding to 0.5 h-1 air exchange.
• Burn modes: steady burn with convective-air shields, sooting burn without shields, and smouldering upon extinction. Steady and sooting burn were performed for both candle types; smouldering was performed only for Candle II. All experiments were repeated two to three times.
• Table 1 total PM2.5 mass emission factors for a single candle: Candle I steady burn 2.4 ± 0.1 mg h-1; Candle II steady burn 0.87 ± 0.14 mg h-1; Candle I sooting 8.9 ± 0.4 mg h-1; Candle II sooting 25.3 ± 0.02 mg h-1.
• Table 1 inorganic-compound emission factors: Candle I steady burn 2.9 ± 0.5 mg h-1; Candle II steady burn 0.92 ± 0.34 mg h-1; Candle I sooting 3.3 ± 0.6 mg h-1; Candle II sooting 1.1 ± 0.6 mg h-1.
• Table 2 smouldering emission for Candle II, reported per single extinction of a single candle: PM2.5 mass 0.72 ± 0.04 mg, elemental carbon 0.03 ± 0.01 mg, organic matter 0.80 ± 0.03 mg, and inorganic compounds 0.11± 0.06 mg.
• Figure 5 note: the chamber EC concentration during Candle II sooting burn extended off-scale; the value is reported as 1424 µg/m3.

Table 3 detailed inorganic component emission factors

Table 3 reports PIXE (n=2) and IC (n=3) component emission factors as averages of steady and sooting burn experiments for each candle. Values are copied as µg h-1.

Source interpretation of metals

• The authors state that very low metal emissions were found for Candle I.
• For Candle II, the main metal compounds detected by PIXE were Cu, Sn, and Co. The authors suggest these may come from wick hardeners or wax additives such as color pigments, noting that Candle II was dark blue and that detected Cu and Co may have originated from color pigments.
• Wick/wax screening by PIXE found only Zn at very low levels in the Candle II wick; other compounds were below the detection limit, Sn was not analyzed in the wick measurements, and no compound was detected with PIXE in the wax.
• Size-resolved PIXE measurements found that for Candle II the only detected impactor components were potassium, tin, and copper; virtually all detected mass was below 1 µm.

Methods (brief)

Candle smoke was generated in a controlled 21.6 m3 stainless-steel chamber with filtered supply air. Four candles of one type were burned in each chamber experiment. Particle mass was measured by TEOM, particle size distributions by SMPS and volatility-SMPS, carbon fractions by thermal-optical OC/EC analysis, water-soluble ions by ion chromatography, elements by PIXE using stacked-filter and impactor samples, and morphology by TEM. Emission factors were calculated using a well-mixed box model with particle-loss correction. The detailed inorganic composition in Table 3 combines PIXE and IC results and is reported as component emission factors, not as candle-product concentration.

Implications

Certification (HMTc): This source supports qualitative and quantitative emissions context for candles or candle-like home-air emission products, especially the presence of Cu, Sn, Co, Zn, and Pb in particle emissions from one dark-blue stearin/paraffin candle type. It should not be treated as a product-content benchmark because the reported values are emitted-particle component emission factors in µg h-1, not finished-candle concentrations.

Courses: The paper is a useful example of basis discipline: product additives, emitted aerosol composition, chamber concentration, and mass emission factors are related but not interchangeable.

App: If home-air emission sources are surfaced, this study can support a note that candle particle emissions may include trace metal components, with Candle II reporting Cu 80 µg h-1, Sn 44 µg h-1, Co 19 µg h-1, Zn 2 µg h-1, and Pb 3 µg h-1.

Wiki pages this source may touch

• home-air-emission-products-other
• copper
• tin
• cobalt
• zinc
• lead

Verification notes

• PDF text was extracted with pdftotext -layout from untitled_29.pdf to /tmp/untitled29.txt; the DOI landing wrapper, abstract, Methods, Tables 1-3, Figure 5 caption, Section 3.4, Section 3.6, and Conclusions were checked against this page.
• Identity checks before creation: DOI 10.1016/j.jaerosci.2008.10.005, title Chemical composition and mass emission factors of candle smoke particles, raw handle MFK_untitled-29, readable-copy SHA-256 9136eedc60c75d017d96ff239bbbd75fa49ccd1172e8019910c263734bdaebec, and candidate cite key pagels2009-candle-smoke-particles were searched in wiki/sources/ and data/evidence/; no existing source page was found.
• Duplicate-file note: cat21_17_lucris_lund_7517427.pdf in the same folder is a corrupt alternate copy exposing the same DOI and Lund portal URL in strings, but pdftotext and pdfinfo cannot read it. The readable untitled_29.pdf copy is used as the canonical raw path for this source page.
• Units: Table 3 component values are copied as µg h-1; Tables 1-2 particle-mass factors are copied as mg h-1 or mg per extinction. No conversion to concentration or finished-product basis was performed.
• Speciation: the metals are reported as elemental components by PIXE. Tin is total Sn, not organotin; lead is Pb, zinc is Zn, cobalt is Co, and copper is Cu.
• Brand firewall: the paper describes candle types and notes that both were manufactured by market-leading Swedish companies, but it does not name brands in the extracted text. This page does not attach brand names to emission values.
• Product slug note: the current taxonomy has scented-candles but no generic unscented/tapered candle slug. Because the source studies tapered candles without stating that they are scented, the page routes through home-air-emission-products-other and records the missing generic candle route here rather than forcing the source into scented-candles.
• Evidence tier: B because this is a peer-reviewed controlled emissions study with detailed methods and repeated chamber experiments, but it tests only two representative candle types and reports emissions rather than product occurrence concentrations.

Page history

The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.